Typical wheelchair designs employ a sturdy frame supporting a seat assembly. The seat assembly includes arm rests and push bars to allow the wheelchair to be pushed by an aide. Attached to the rear of the frame is a pair of drive wheels. The drive wheels are typically large diameter wheels attached to a central hub with spokes. Push rims are mounted to the drive wheels to allow the wheelchair occupant to propel the chair using their arms and upper body. A smaller pair of pivoting castor wheels is attached to the front of the frame to provide steerability. Extending down from the lower front of the wheelchair frame is a footrest system to support the lower legs. The footrest system typically includes a pair of bars, one mounted to each side of the frame. Attached to each bar is a footrest, which typically may be pivoted up and out of the way to provide clearance if the occupant so desires. Adjustment mechanisms allow each bar to slide in adjustment relative to the frame to accommodate the differing heights and leg lengths of the wheelchair occupant.
One drawback to existing wheelchairs is that the footrest system, once adjusted for the particular size of the occupant, remains locked in a fixed position. As a result, the occupant's legs are stationary while seated in the wheelchair. Over extended periods of time, a wheelchair occupant who is not able to move their legs on their own may develop atrophy in the leg muscles and contracture of the leg joint ligaments. Moreover, prolonged leg immobility substantially increases risks of blood clotting (venous thrombosis) or arterial blockage (peripheral arterial disease). Either of these problems with blood circulation can cause death either incrementally via necrosis and infection, which may be averted by amputation; or, more immediately, via dislodgement of a clot or blockage that subsequently blocks a cardiac, pulmonary, or cranial artery.
Efforts have been made to prevent muscle atrophy and contractures, as well as circulatory deficiencies, by providing for continuous or periodic motion of a wheelchair occupant's legs. For example, one prior art solution is provided by a wheelchair cycle apparatus that includes a frame to which is attached a connecting device for connecting the frame to a wheelchair. A drive wheel and driven wheel are attached to the frame. A pair of pedals are attached to either the drive wheel or the driven wheel depending upon whether the user can move his/her own legs. A chain connects the drive wheel to the driven wheel. The wheelchair cycle apparatus may be connected to the frame of a wheelchair to produce a wheelchair assembly that enables a wheelchair occupant to exercise his/her own legs while seated in the wheelchair. However, it is believed difficult to keep a user's feet connected with the revolving pedals in cases where the user's legs are only passively mobile (i.e. for paraplegic wheelchair users, or for those who have suffered less permanent injuries such as stroke, knee or hip replacement, or bone fracture). Possibilities of having feet slip off the revolving pedals, or improper modes of keeping feet on the pedals, present a risk of injury to the feet and legs with consequent risks of infection.
As another example, a wheelchair may be provided with pivoting leg rests. The wheelchair may include a drive assembly linking the pivoting leg rests to the rear wheels, such that a user seated in the wheelchair can propel the chair forward by repeated pivoting motions of the user's lower legs about their knee joints. However, such a drive assembly is usable only by a wheelchair user with actively movable legs. A user with only passively mobile legs cannot utilize the drive assembly.
Thus, a need remains for a wheelchair apparatus that will reliably maintain circulation in the passively mobile or weakened legs of a wheelchair user.